I'm guessing that this was fought in the UK, anything to do with Edward I?...
Bosworth Field?...
Was it the final battle of the war of the roses?...
Towton - 1461 ? But could they be described as British at that time before unification ?
Doesn't a yellow flag in a port...mean plague/quarantine
Yellow flag in F! means danger ahead
An a yellow flag rthrown in in US football is a penalty (for or against)
So fits 2 qnd 3 but not 1...what other flag could it be...
Chequered...would have to google that tho
Gandhi was a news reporter in South Africa during the Boer War - could it be Spion Kop where there was a battle involving a Liverpool regiment - from which the club gets the name.